This project is designed to provide a prospective longitudinal assessment of the natural history of HIV infection in mothers and their infants with special emphasis on the definition of factors which promote progression to clinical disease in HIV infected mothers and factors which discriminate HIV infected from uninfected infants born to these mothers. We will determine whether pregnancy promotes progression of disease in HIV antibody positive women as well as assess the effects of HIV infection of pregnancy outcome, including the magnitude of risk and route of perinatal transmission. We will identify those epidemiologic, virologic, or immunologic factors which might predict progression of disease and/or vertical transmission. We will develop strategies to diagnose HIV infection in infants at high risk for AIDS secondary to vertical transmission from infected mothers as soon after the infants birth as is possible, We will identify early clinical and/or immunological changes which will distinguish infected from uninfected infants of HIV sero-positive women and investigate the early developmental and neurological consequences of HIV infection in children born to these women. By identifying the clinical, immunological and virological factors that influence the biology of perinatal HIV infection we hope to develop strategies to prevent vertical transmission of HIV and its associated sequelae. By identifying methods for the early diagnosis of HIV infection in the Newborn, we will allow for early treatment in hopes of ameliorating the morbidity and preventing the mortality of pediatric AIDS.